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No description available.

No description available.

No description available.

No description available.

Pharmaceuticals, personal care products and dissolved organic matter (OM) are introduced to soil via irrigation with reclaimed wastewater. This thesis examines the basic factors that influence sorption of these components in soil. Sorption of dissolved OM samples of varying composition to clay surfaces was examined. Results indicate that preferential sorption is dependent on clay type but not necessarily OM composition. Analysis of soils revealed aliphatic components, carbohydrates and amino acids are prevalent at the soil-water interface whereas aromatics are inaccessible at the soil-water interface. No clear relationship between sorption affinity of 17β-estradiol, sulfamethoxazole, carbamazepine and phenanthrene and soil OM aromaticity or aliphaticity was observed. A negative relationship between sorption and O-alkyl content may be due to these components blocking contaminant access to high affinity sorption sites. Therefore, application of reclaimed wastewater to soils with O-alkyl-rich OM may result in higher mobility of contaminants.

Pharmaceuticals, personal care products and dissolved organic matter (OM) are introduced to soil via irrigation with reclaimed wastewater. This thesis examines the basic factors that influence sorption of these components in soil. Sorption of dissolved OM samples of varying composition to clay surfaces was examined. Results indicate that preferential sorption is dependent on clay type but not necessarily OM composition. Analysis of soils revealed aliphatic components, carbohydrates and amino acids are prevalent at the soil-water interface whereas aromatics are inaccessible at the soil-water interface. No clear relationship between sorption affinity of 17β-estradiol, sulfamethoxazole, carbamazepine and phenanthrene and soil OM aromaticity or aliphaticity was observed. A negative relationship between sorption and O-alkyl content may be due to these components blocking contaminant access to high affinity sorption sites. Therefore, application of reclaimed wastewater to soils with O-alkyl-rich OM may result in higher mobility of contaminants.

Apelin, the endogenous ligand to the apelin receptor, is a small peptide involved with cardiovascular regulation. Using nuclear magnetic resonance (NMR) spectroscopy, I demonstrate that at low temperature, residues R6-L9 and G13-F17 of apelin are more structured than the rest of the peptide. I also study the interactions of apelin with sodium dodecylsulphate (SDS), dodecylphosphocholine (DPC) and 1-palmitoyl-2-hydroxy-sn- glycero-3-[phospho-RAC-(1-glycerol)] (LPPG) micelles. Apelin binds to SDS micelles through residues R6-L9, with structure being induced in this region as well as the C- terminus of the peptide. The binding to micelles along with the corresponding change in structure make it likely that apelin binds to the apelin receptor following the membrane catalysis hypothesis. NMR spectroscopy was used to determine the structure of the N- terminal tail and first transmembrane segment of the apelin receptor (AR55) in DPC micelles. AR55 has two disrupted helices from D14-K25 and from A29-K57. The second helix is the membrane spanning region of AR55 and has a significant kink located at N46. Mutagenesis of the apelin receptor and functional assays indicate that G42, G45 and N46 are essential for the proper trafficking and function of AR. In the N-terminal tail, the functionally critical residues E20 and D23 form an anionic face that could take part in initial binding of apelin to AR. The structure of AR55 was also determined in SDS micelles, LPPG micelles and a 1:1 water: 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) solution. Overall, the micelle spanning region of AR55 has a consistent structure with a kink near N46. The N-terminal tail of AR55 is more variable, having similar structures in the micelle conditions but being largely helical in 50% HFIP. NMR relaxation experiments indicate that the N-terminal tail of AR55 undergoes much more motion in LPPG micelles compared to SDS and DPC micelles. Finally, I created a program named MC-HELAN that characterizes the kinks that occur in protein helices. I used MC- HELAN to analyze all non-redundant membrane protein structures as of March 2010. Membrane protein helix kinks are remarkably common and diverse. Initial attempts to predict membrane protein kinks using only the protein sequence were unsuccessful.

Solid state NMR has the ability to obtain detailed structural information at the molecular level in materials. This has led to the development of a large number of high resolution techniques, some of which utilize multiple pulse methods. The behaviour of these multiple pulse techniques has, to date, been explained using either relaxation or spin dynamics. Ultimately, an explanation based on a combination of both dynamics is required in order to properly understand the underlying mechanism of these techniques. This work presents an explanation of the experimental behaviour observed for three multiple pulse domain selection techniques: the DIVAM, Direct DIVAM, and Refocused DIVAM sequences. This is based on a combination of spin and relaxation dynamics and is accomplished using both analytical expressions and simulations obtained using a general simulation program for solid-state NMR spectroscopy (SIMPSON). / xviii, 179 leaves ; 29 cm

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